Orderwire communication system

Abstract

An orderwire scheme for a multichannel repeated communication network contains an auxiliary communication link that is coupled to communication sites along the network and is configured of a pair of orderwire links each formed of a conventional interstitial copper wire pair. To carry out supervisory functions with respect to each of the stations along the communication link, messages are conveyed from a control facility coupled to or as part of the network to respective stations along the link in the form of command instructions. These messages may contain a request for information from the addressed site as to equipment conditions at the site or a directive that the equipment at the site perform a particular task. In reply to the command message sent to it the addressed site returns a response message back to the control facility representative of the action taken including any data requested by the instructions. In addition to providing a distributed communication link over which supervisory command and response messages can be transmitted among the stations along the orderwire link, a further facility for conveying voice communications over the same orderwire link is provided. In order to implement the exchange of command and response messages among the various sites of the network, supervisory signals are transmitted using digitally encoded ON/OFF keying of frequency tone signals.

What is claimed is: 
     
       1. For use in a communication system wherein information signals are to be conveyed among a plurality of stations distributed along a shared communication link, said link having a first portion for carrying messages in a first direction along said link and a second portion for carrying messages in a second direction along said link, a station transceiver for receiving messages transmitted to it and transmitting response messages in reply thereto comprising: first means, coupled to said link, for receiving a first incoming message transmitted over said first portion of said link at a first prescribed carrier frequency; and   second means, coupled to said link, for transmitting an outgoing message over said second portion of said link at said first prescribed carrier frequency and over said first portion of said link at a second prescribed carrier frequency different from said first prescribed frequency.   
     
     
       2. A station transceiver according to claim 1, wherein said first means further comprises means, coupled to said link, for receiving a second incoming message transmitted over said second portion of said link at said second carrier prescribed frequency; and wherein said second means includes means for transmitting said outgoing response message in response to receipt of either of said first and second incoming messages.   
     
     
       3. A station transceiver according to claim 2, wherein messages conveyed over said link are in the form of digitally encoded signals carried on said first and second prescribed carrier frequencies. 
     
     
       4. A station transceiver according to claim 2, wherein said messages conveyed over said link are in the form of amplitude modulated ones of said first and second prescribed carrier frequencies. 
     
     
       5. A station transceiver according to one of claims 1, 3 and 4, wherein said transceiver further comprises means for receiving voice signals carried over said link and means for transmitting voice signals onto said link in response to voice signals applied externally thereto. 
     
     
       6. A station transceiver according to one of claims 2, 3 and 4, wherein said transceiver further comprises means for receiving voice signals carried over either of said first and second portions of said link, and means for transmitting voice signals externally applied thereto onto both said first and second portions of said link. 
     
     
       7. A station transceiver according to claim 3, wherein said first means includes means for removing the digitally encoded message from the received carrier frequency, and means for storing said digitally encoded message in preparation for the generation and transmission of an outgoing message in reply thereto. 
     
     
       8. A station transceiver according to claim 2, wherein said transceiver includes dual frequency detector/generator for detecting incoming messages on either of said first and second prescribed car ier frequencies and for generating said first and second prescribed carrier frequencies on which an outgoing response message is to be transmitted. 
     
     
       9. A station transceiver according to claim 7, wherein second means includes means for transmitting as part of said outgoing response message said stored digitally encoded message. 
     
     
       10. A station transceiver according to claim 7, wherein each message includes an address portion identifying the station to whom the message is transmitted, and said first means includes means for storing said digitally encoded message upon detecting that the address portion of a message transmitted over said link corresponds to the address of its associated station. 
     
     
       11. A station transceiver according to claim 8, wherein each message includes an address portion identifying the station to whom the message is transmitted, and said first means includes means for storing said digitally encoded message upon detecting that the address portion of a message transmitted over said link corresponds to the address of its associated station; and wherein first means includes means for inhibiting said second means from transmitting an outgoing response message on said first and second frequencies until said storing means detects that the address portion of a message transmitted over said link corresponds to the address of its associated station. 
     
     
       12. For use in a communication system wherein information signals are to be conveyed among a plurality of stations distributed along a shared communication link, said link having a first portion for carrying messages in a first direction along said link and a second portion for carrying messages in a second direction along said link, a station transceiver for transmitting to another station, and for receiving messages transmitted to it and transmitting response messages in reply thereto comprising: first means, coupled to said link, for transmitting an outgoing message on a selected one of first and second prescribed carrier frequencies over said first portion of said link; and   second means, coupled to said link, for receiving an incoming message on either of said first and second prescribed carrier frequencies over said second portion of said link.   
     
     
       13. A station transceiver according to claim 12, wherein said first means includes means for transmitting a first outgoing message on said first prescribed carrier frequency over said first portion of said link to said another station on said link, so as to cause said another station to transmit a response message, and wherein said second means includes means for receiving said response message transmitted on said first prescribed carrier frequency on said second portion of said link. 
     
     
       14. A station transceiver according to one of claims 12 and 13, wherein said second means includes means for receiving an incoming message on said second prescribed carrier frequency over said second portion of said link and causing said first means to transmit an outgoing message in response thereto on said second prescribed carrier frequency over said first portion of said link. 
     
     
       15. A station transceiver according to claim 12, wherein said transceiver further comprises means for receiving voice signals carried over said link and means for transmitting voice signals onto said link in response to voice signals applied externally thereto. 
     
     
       16. A station transceiver according to claim 12, wherein messages conveyed over said link are in the form of digitally encoded signals carried on a respective one of said first and second prescribed carrier frequencies. 
     
     
       17. A station transceiver according to claim 12, wherein said transceiver further includes means for receiving voice signals carried over said second portion of said link, and means for transmitting voice signals externally applied thereto on said first portion of said link. 
     
     
       18. A station transceiver according to claim 16, wherein said second means includes means for removing the digitally encoded message from the received carrier frequency, and means for storing said digitally encoded message in preparation for the generation and transmission of an outgoing message in response thereto. 
     
     
       19. A station transceiver according to one of claims 12, 13 and 14, wherein said transceiver includes a frequency detector/generator for detecting incoming messages on either of said first and second prescribed carrier frequencies and for generating said second prescribed carrier frequency on which an outgoing response message is to be transmitted. 
     
     
       20. A station transceiver according to claim 14, wherein messages conveyed over said link are in the form of digitally encoded signals carried on a respective one of said first and second prescribed carrier frequencies. 
     
     
       21. A station transceiver according to claim 20, wherein said second means includes means for removing the digitally encoded message from the received carrier frequency, and means for storing said digitally encoded message in preparation for the generation and transmission of an outgoing message in response thereto. 
     
     
       22. A station transceiver according to claim 21, wherein said first means includes means for transmitting as part of an outgoing response message said stored digitally encoded message. 
     
     
       23. A station transceiver according to claim 18, wherein each message includes an address portion identifying the station to whom the message is transmitted, and said second means includes means for storing said digitally encoded message upon detecting that the address portion of a message transmitted over said link corresponds to the address of its associated station. 
     
     
       24. A station transceiver according to claim 19, wherein each message includes an address portion identifying the station to whom the message is transmitted, and said second means includes means for storing said digitally encoded message upon detecting that the address portion of a message transmitted over said link corresponds to the address of its associated station; and wherein said second means includes means for inhibiting said first means from transmitting an outgoing message on said second frequency until said storing means detects that the address portion of a message transmitted over said link corresponds to the address of its associated station. 
     
     
       25. A communication system wherein information signals are to be conveyed among a plurality of stations distributed along a shared communications link, said link having a first portion for carrying messages in a first direction along said link and a second portion for carrying messages in a second direction along said link, each of said stations having input/output devices that may be impacted by messages carried over said link, comprising: a first terminal station coupled to said link and having a transceiver for transmitting outgoing messages over said first portion of said link to one of a plurality of intermediate stations and a second terminal station at a first prescribed carrier frequency and receiving messages, conveyed over said second portion of said link from one of said intermediate and second terminal stations, at either of said first prescribed carrier frequency and a second prescribed carrier frequency;   a second terminal station coupled to said link and having a transceiver for transmitting outgoing messages over said second portion of said link to one of said intermediate and first terminal stations at said second prescribed carrier frequency and receiving messages, conveyed over said first portion of said link from one of said intermediate and first terminal stations, at either of said first and second prescribed carrier frequencies; and   a plurality of intermediate stations coupled to said link, each having a transceiver for receiving incoming messages from said first terminal station on said first portion of said link at said first prescribed carrier frequency and for receiving incoming messages from said second terminal station on said second portion of said link at said second prescribed carrier frequency, and for transmitting outgoing response messages on said first portion of said link at said second prescribed carrier frequency and on said second portion of said link at said first prescribed carrier frequency.   
     
     
       26. A communication system according to claim 25, wherein each of said first and second terminal stations comprises means for transmitting outgoing messages in response to receipt of messages at either of said first and second prescribed carrier frequencies. 
     
     
       27. A communication system according to claim 25, wherein messages conveyed over said link are in the form of digitally encoded signals carried on said first and second prescribed carrier frequencies. 
     
     
       28. A communication system according to claim 25, wherein each of said stations further comprises means for receiving voice signals carried over said link and means for transmitting voice signals over said link in response to voice signals applied externally thereto. 
     
     
       29. A communication system according to claim 27, wherein each station includes means for removing the digitally encoded message from the received carrier frequency and means for storing said digitally encoded message in preparation for the generation and transmission of an outgoing message in reply thereto. 
     
     
       30. A communication system according to claim 25, wherein each terminal station includes a dual frequency detector/generator for detecting incoming messages on either of said first and second prescribed carrier frequencies and for generating one of said first and second prescribed carrier frequencies on which an outgoing message is to be transmitted. 
     
     
       31. A communication system according to claim 29, wherein each message includes an address portion identifying the station to whom the message is transmitted, and each station includes means for storing said digitally encoded message upon detecting that the address portion of a message transmitted over said link corresponds to its own address. 
     
     
       32. A communication system according to claim 25, wherein each of said terminal stations is coupled to receive information signals to be transmitted as a message to impact upon the input/output device associated with one of said stations and includes means for coupling said message to the station with which said input/output device is associated. 
     
     
       33. A communication system according to claim 32, wherein a terminal station includes means for causing an information signal generated thereat for impacting upon the input/output device associated with said station exclusive of said link. 
     
     
       34. A communication system according to claim 25, wherein each message includes an address portion identifying the station to whom the message is transmitted, and each station includes means for storing said digitally encoded message upon detecting that the address portion of a message transmitted over said link corresponds to its own address. 
     
     
       35. A communication system according to claim 34, wherein a terminal station includes means for causing an information signal generated thereat as an outgoing message to be coupled to said link and to said storing means exclusive of the transmission of said outgoing message over said link. 
     
     
       36. For use in a communication system wherein information signals are to be conveyed among a plurality of stations distributed along a shared communication link, said link having a first portion for carrying messages in a first direction along said link and a second portion for carrying messages in a second direction along said link, a station transceiver for receiving messages transmitted to it and transmitting response messages in reply thereto comprising: first means, coupled to said link, for receiving a first incoming message transmitted over said first portion of said link at one of first and second prescribed carrier frequencies; and   second means, coupled to said link, for transmitting an outgoing message over said second portion of said link at one of said first and second prescribed carrier frequencies and over said first portion of said link at the other of said first and second prescribed carrier frequencies.   
     
     
       37. A station transceiver according to claim 36, wherein said first means comprises means, coupled to said link, for receiving a first incoming message transmitted over said first portion of said link at said first prescribed carrier frequency; and   said second means includes means for transmitting an outgoing message over said second portion of said link at said second prescribed frequency and over said first portion of said link at said first prescribed carrier frequency.   
     
     
       38. A station transceiver according to claim 36, wherein said first means further comprises means, coupled to said link, for receiving a second incoming message transmitted over said second portion of said link at said second carrier prescribed frequency; and wherein said second means includes means for transmitting said outgoing message in response to receipt of either of said first and second incoming messages.   
     
     
       39. A station transceiver according to claim 38, wherein messages conveyed over said link are in the form of digitally encoded signals carried on said first and second prescribed carrier frequencies. 
     
     
       40. A station transceiver according to claim 36, wherein said second means includes means responsive to a reduction of received level of carrier frequencies below a prescribed threshold on said first portion of said link, for generating the carrier frequency corresponding to reduced level carrier frequency and causing the generated carrier frequency to be applied to said first portion of said link. 
     
     
       41. A station transceiver according to claim 38, wherein said second means includes means, responsive to a reduction of level of each of said carrier frequencies below a prescribed threshold on said first and second portions of said link, for generating the reduced level carrier frequency and causing the generated carrier frequency to be applied to the corresponding one of said first and second portions of said link. 
     
     
       42. A station transceiver according to claim 37, wherein said second means includes means responsive to a reduction of level of carrier frequencies below a prescribed threshold on said first portion of said link, for generating the carrier frequency corresponding to the reduced level carrier frequency and causing the generated carrier frequency to be applied to said first portion of said link. 
     
     
       43. A station transceiver according to claim 42, wherein said second means further includes means for inhibiting the transmission of messages over said first portion of said link in response to said reduction in level of carrier frequency. 
     
     
       44. A station transceiver according to claim 41, wherein said second means includes means for inhibiting the transmission of messages over that one of said first and second portions of said link other than the portion of the link having a reduction in carrier frequency, in response to said reduction in level of carrier frequency. 
     
     
       45. A station transceiver according to claim 38, wherein said messages conveyed over said link are in the form of amplitude modulated ones of said first and second prescribed carrier frequencies, and wherein said transceiver further comprises means for receiving voice signals carried over said link and means for transmitting voice signals onto said link in response to voice signals applied externally thereto. 
     
     
       46. A station transceiver according to claim 45, wherein said transceiver further comprises means for receiving voice signals carried over either of said first and second portions of said link, and means for transmitting voice signals externally applied thereto onto both said first and second portions of said link. 
     
     
       47. A station transceiver according to claim 39, wherein said first means includes means for removing the digitally encoded message from the received carrier frequency, and means for storing said digitally encoded message in preparation for the generation and transmission of an outgoing message in reply thereto. 
     
     
       48. A station transceiver according to claim 38, wherein said transceiver includes a dual frequency detector/generator for detecting incoming messages on either of said first and second prescribed carrier frequencies and for generating said first and second prescribed carrier frequencies on which an outgoing message is to be transmitted. 
     
     
       49. A station transceiver according to claim 47, wherein second means includes means for transmitting as part of said outgoing message said stored digitally encoded message. 
     
     
       50. A station transceiver according to claim 47, wherein each message includes an address portion identifying the station to whom the message is transmitted, and said first means includes means for storing said digitally encoded message upon detecting that the address portion of a message transmitted over said link corresponds to the address of its associated station. 
     
     
       51. A station transceiver according to claim 48, wherein each message includes an address portion identifying the station to whom the message is transmitted, and said first means includes means for storing said digitally encoded message upon detecting that the address portion of a message transmitted over said link corresponds to the address of its associated station; and wherein said first means includes means for inhibiting said second means from transmitting an outgoing message on said first and second frequencies until said storing means detects that the address portion of a message transmitted over said link corresponds to the address of its associated station. 
     
     
       52. For use in a communication system wherein information signals are to be conveyed among a plurality of stations distributed along a shared communication link, said link having a first portion for carrying messages in a first direction along said link and a second portion for carrying messages in a second direction along said link, a station transceiver for transmitting to another station, and for receiving messages transmitted to it and transmitting response messages in reply thereto comprising: first means, coupled to said link, for transmitting an outgoing message on a selected one of first and second prescribed carrier frequencies over said first portion of said link; and   second means, coupled to said link, for receiving an incoming message on the other of said first and second prescribed carrier frequencies over said second portion of said link.   
     
     
       53. A station transceiver according to claim 52, wherein said second means includes means for receiving an incoming message on said second prescribed carrier frequency over said second portion of said link and causing said first means to transmit an outgoing message in response thereto on said first prescribed carrier frequency over said first portion of said link. 
     
     
       54. A station transceiver according to claim 53, wherein said transceiver further comprises means for receiving voice signals carried over said link and means for transmitting voice signals onto said link in response to voice signals applied externally thereto. 
     
     
       55. A station transceiver according to claim 52, wherein messages conveyed over said link are in the form of digitally encoded signals carried on a respective one of said first and second prescribed carrier frequencies. 
     
     
       56. A station transceiver according to claim 52, wherein said transceiver further includes means for receiving voice signals carried over said second portion of said link, and means for transmitting voice signals externally applied thereto on said first portion of said link. 
     
     
       57. A station transceiver according to claim 55, wherein said second means includes means for removing the digitally encoded message from the received carrier frequency, and means for storing said digitally encoded message in preparation for the generation and transmission of an outgoing message in response thereto. 
     
     
       58. A station transceiver according to claim 52, wherein said transceiver includes a frequency detector/generator for detecting incoming messages on either of said first and second prescribed carrier frequencies and for generating said second prescribed carrier frequency on which an outgoing response message is to be transmitted. 
     
     
       59. A station transceiver according to claim 53, wherein messages conveyed over said link are in the form of digitally encoded signals carried on a respective one of said first and second prescribed carrier frequencies. 
     
     
       60. A station transceiver according to claim 59, wherein said second means includes means for removing the digitally encoded message from the received carrier frequency, and means for storing said digitally encoded message in preparation for the generation and transmission of an outgoing message in response thereto. 
     
     
       61. A station transceiver according to claim 60, wherein said first means includes means for transmitting as part of an outgoing response message said stored digitally encoded message. 
     
     
       62. A station transceiver according to claim 57, wherein each message includes an address portion identifying the station to whom the message is transmitted, and said second means includes means for storing said digitally encoded message upon detecting that the address portion of a message transmitted over said link corresponds to the address of its associated station. 
     
     
       63. A station transceiver according to claim 58, wherein each message includes an address portion identifying the station to whom the message is transmitted, and said second means includes means for storing said digitally encoded message upon detecting that the address portion of a message transmitted over said link corresponds to the address of its associated station; and wherein said second means includes means for inhibiting said first means from transmitting an outgoing message on said second frequency until said storing means detects that the address portion of a message transmitted over said link corresponds to the address of its associated station. 
     
     
       64. A station transceiver according to claim 53, wherein said second means includes means, responsive to a reduction of level of carrier frequency below a prescribed threshold on either of said first and second portions of said link, for generating the carrier frequency corresponding to the reduced level carrier frequency and causing the generated carrier frequency to be applied to the corresponding portion of said link by said first means. 
     
     
       65. A station transceiver according to claim 64, wherein said second means includes means for inhibiting said first means from transmitting an outgoing message to that portion of said link other than said corresponding portion of said link in response to said reduction inlevel of carrier frequency. 
     
     
       66. A station transceiver according to claim 52, wherein sais first means includes means for transmitting a first outgoing message on said first prescribed carrier frequency over said first portion of said link to said another station on said link, so as to cause said another station to transmit a response message, and wherein said second means includes means for receiving said response message transmitted on said second prescribed carrier frequency on said second portion of said link. 
     
     
       67. A communication system wherein information signals are to be conveyed among a plurality of stations distributed along a shared communications link, said link having a first portion for carrying messages in a first direction along said link and a second portion for carrying messages in a second direction along said link, each of said stations having input/output devices that may be impacted by messages carried over said link, comprising: a first terminal station coupled to said link and having a transceiver for transmitting outgoing messages over said first portion of said link to one of a plurality of intermediate stations and a second terminal station at a first prescribed carrier frequency and receiving messages, conveyed over said second portion of said link from one of said intermediate and second terminal stations, at a second prescribed carrier frequency;   a second terminal station coupled to said link and having a transceiver for transmitting outgoing messages over said second portion of said link to one of said intermediate and first terminal stations at said second prescribed carrier frequency and receiving messages, conveyed over said first portion of said link from one of said intermediate and first terminal stations, at said first prescribed carrier frequency; and   a plurality of intermediate stations coupled to said link, each having a transceiver for receiving incoming messages from said first terminal station on said first portion of said link at said first prescribed carrier frequency and for receiving incoming messages from said second terminal station on said second portion of said link at said second prescribed carrier frequency, and for transmitting outgoing response messages on said first portion of said link at said first prescribed carrier frequency and on said second portion of said link at said second prescribed carrier frequency.   
     
     
       68. A communication system according to claim 67, wherein each transceiver includes means responsive to a reduction of carrier frequency on a respective portion of said link by way of which the transceiver receives messages, for generating a carrier frequency corresponding to the reduced carrier frequency and causing the generated carrier frequency to be applied to said respective portion of said link. 
     
     
       69. A communication system according to claim 68, wherein messages conveyed over said link are in the form of digitally encoded signals carried on said first and second prescribed carrier frequencies. 
     
     
       70. A communication system according to claim 68, wherein each of said stations further comprises means for receiving voice signals carried over said link and means for transmitting voice signals over said link in response to voice signals applied externally thereto. 
     
     
       71. A communication system according to claim 69, wherein each station includes means for removing the digitally encoded message from the received carrier frequency and means for storing said digitally encoded messages in preparation for the generation and transmission of an outgoing message in reply thereto. 
     
     
       72. A communication system according to claim 67, wherein each terminal station includes a dual frequency detector/generator for detecting incoming messages on either of said first and second prescribed carrier frequencies and for generating that one of said first and second prescribed carrier frequencies on which an outgoing message is to be transmitted. 
     
     
       73. A communication system according to claim 71, wherein each message includes an address portion identifying the station to whom the message is transmitted, and each station includes means for storing said digitally encoded message upon detecting that the address portion of a message transmitted over said link corresponds to its own address. 
     
     
       74. A communication system according to claim 67, wherein each of said terminal stations is coupled to receive information signals to be transmitted as a message to impact upon the input/output device associated with one of said stations and includes means for coupling said message to the station with which said input/out device is associated. 
     
     
       75. A communication system according to claim 74, wherein a terminal station includes means for causing an information signal generated thereat for impacting upon the input/output device associated with said station exclusive of said link. 
     
     
       76. A communication system according to claim 67, wherein each message includes an address portion identifying the station to whom the message is transmitted, and each station includes means for storing said digitally encoded message upon detecting that the address portion of a message transmitted over said link corresponds to its own address. 
     
     
       77. A communication system according to claim 76, wherein a terminal station includes means for causing an information signal generated thereat as an outgoing message to be coupled to said link and to said storing means exclusive of the transmission of said outgoing message over said link. 
     
     
       78. A communication system according to claim 68, wherein each transceiver further includes means for inhibiting the transmission of messages over that portion of said link other than said respective portion of said link in response to said reduction in carrier frequency.